Method and system for profiling users based on their relationships with content topics

ABSTRACT

An affinity generation system according to the present invention analyzes a profiled user&#39;s authorship and document usage within an ‘intranet’ to create a set of affinities between documents and topical classifications used in a hierarchical content catalog. These affinities are weighted depending on the system usage and amount of collected evidence. Once a certain threshold has been reached, the threshold being fixed or dynamically set to achieve a desired policy, the affinities are published into the content catalog. The user looking for specific expertise can then search or browse the content catalog and find both documents and people with strong affinities to the selected content area.

CROSS REFERENCE TO RELATED APPLICATION

This is a continuation of application Ser. No. 09/401,581, filed Sep.22, 1999, now U.S. Pat. No. 7,000,194 B1.

COPYRIGHT NOTICE

A portion of the disclosure of this patent document contains materialwhich is subject to copyright protection. The copyright owner has noobjection to the facsimile reproduction by anyone of the patent documentor the patent disclosure, as it appears in the Patent and TrademarkOffice patent files or records, but otherwise reserves all copyrightrights whatsoever.

RELATED APPLICATIONS

This application is related to commonly owned application Ser. No.09/192,047 titled METHOD AND SYSTEM FOR CONVEYING EXPERTISE BASED ONDOCUMENT USAGE, filed Nov. 13, 1998, now U.S. Pat. No. 6,377,983 B1,which is hereby incorporated by reference into this application.

This application is related to commonly owned application Ser. No.09/191,587 titled METHOD AND SYSTEM FOR SUMMARIZING TOPICS OF DOCUMENTSBROWSED BY A USER, filed Nov. 13, 1998, now U.S. Pat. No. 6,356,898 B2which is hereby incorporated by reference into this application.

BACKGROUND OF THE INVENTION

The invention disclosed herein relates to cooperative computingenvironments and information retrieval and management methods andsystems. More particularly, the present invention relates to methods andsystems for capturing and generating useful information about a user'saccess and use of data on a computer system, such as in the form ofdocuments stored on remote servers, and making such useful informationavailable to others.

Most organizations that have grown past a few hundred employees havesome form of directory and usually have made some attempt to augmentthis directory with personal profile attributes such as memberships,position title or project affiliations. Many have attempted to expandeach person's profile by adding skills inventory, educational backgroundor professional accomplishments. Many of these efforts have beensuccessful, but most have not fulfilled their promise. The effortrequired to update and maintain such a profile and the subjective natureof self description leads to inaccuracies or stale data.

Most such “people finder” systems fail due to the lack of timely updatesto the expert's profiles. In addition, many knowledgeable workers do notconsider their experience to be valuable to others and may overlook thiswhen manually completing profile forms. The result is that most manuallybuilt expertise locator systems are irrelevant or become outdated andeventually fail.

There is therefore a need for a system for automatically and dynamicallyidentifying people as having affinity to or being experts in varioustopics or content and making this information known to others.

SUMMARY OF THE INVENTION

It is an object of the present invention to solve the problems describedabove with existing people finder systems.

It is another object of the present invention to automate a process oflocating people within an organization having some expertise in a topic.

Some of the above and other objects are achieved by a method, system andcomputer program for profiling a user based on the user's activity. Themethod involves assigning one or more topics to each of a plurality ofdocuments based at least in part upon content contained in thedocuments, maintaining an affinity variable associated with the user foreach of one or more of the topics assigned to a document attributed tothe user, determining whether a first affinity variable for the user fora given topic has reached a threshold, and associating the user with thegiven topic for the first affinity variable which reaches the threshold.

In some embodiments, an affinity generation system according to thepresent invention analyzes a profiled user's authorship and documentusage within an ‘intranet’ to create a set of affinities betweendocuments and topical classifications used in a hierarchical contentcatalog. These affinities are weighted depending on the system usage andamount of collected evidence. Once a certain threshold has been reached,the threshold being fixed or dynamically set to achieve a desiredpolicy, the affinities are published into the content catalog. The userlooking for specific expertise can then search or browse the contentcatalog and find both documents and people with strong affinities to theselected content area.

The affinity generation system is used to populate and maintain aperson's interest and skills profile. This profile can be a part of acorporate directory system or an independent repository. The profile isused initially as part of a ‘people finder system’ to locate expertisewithin an organization, but can also be exploited to assist in thecreation of ad hoc work teams, review boards, etc. in addition to ageneral analysis of skills and expertise assets within an organization.

The affinity generation system uses automation to create and maintainboth the user profiles and published affinities. In addition, theleveraged use of an accepted hierarchical content catalog and themultidimensional content classification scheme insures an accurate setof topical affinities that are easy to relate to the activities of theorganization.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is illustrated in the figures of the accompanying drawingswhich are meant to be exemplary and not limiting, in which likereferences are intended to refer to like or corresponding parts, and inwhich:

FIG. 1 is a block diagram of an exemplary system for profiling usersbased upon document usage and updating a content catalog in accordancewith one embodiment of the present invention;

FIG. 2 is flow chart showing a general process of profiling usersperformed by the system shown in FIG. 1;

FIGS. 3A-3D contain a flow chart showing the process of profiling usersin greater detail in accordance with one embodiment of the presentinvention;

FIG. 4 is an exemplary screen display showing results from a searchthrough the content catalog shown in FIG. 1 for a selected topic; and

FIG. 5 is an exemplary screen display showing a user profile linked tothe search results screen shown in FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The preferred embodiments of a system, method, and article ofmanufacture containing software programs in accordance with the presentinvention are described with reference to the drawings in FIGS. 1-5.

Referring to FIG. 1, one embodiment of the system 10 of the presentinvention includes, among other things a document management system 12for storing and administrating a plurality of documents 13, a contentcatalog 14, and a user profile repository 16. For purposes of thisdescription, documents 13 include any types of files containing contentsuch as database files, text documents, graphics, video or audio files,newsgroup files, online bulletin board files, Lotus NOTES documents,e-mail files, chat discussion files, etc., and the document managementsystem 12 is a conventional application program for managing thedocuments. The system 10 is accessible to a plurality of users 11, whocan create, access, edit, send, and otherwise manipulate or use thedocuments 13 through the document management system 12. In someembodiments, the system 10 may be implemented as a server and the users11 as clients connectable to the server over an intranet, extranet orthe Internet.

The content catalog 14 is hierarchical taxonomy or collection of contentcategories or topics with links to the documents 13. The content catalogincludes a user interface for allowing browsing of the hierarchy ordirectly searching the topics for relevant documents. The contentcatalog 14 may be of the well-known type, sometimes referred to as aknowledge map, knowledge catalog or content taxonomy. Several publicexamples of a content catalogs exist on the Internet today, such asYAHOO! and the NETSCAPE Open Directory, and various vendors havetoolsets for creating content catalogs for a corporate intranet,including GRAPEVINE, AUTONOMY, and OPENTEXT, etc.

A topic generation program 18 serves as an automatic multidimensionalclassification program to add new documents 13 to the collection in thecontent catalog 14. The topic generation program 18 may be of the typeemployed by web search engines to collect and classify various data. Anexample of such a program is described in U.S. Pat. No. 5,659,732,issued Aug. 19, 1997, entitled DOCUMENT RETRIEVAL OVER NETWORKS WHEREINRANKING AND RELEVANCE SCORES ARE COMPUTED AT THE CLIENT FOR MULTIPLEDATABASE DOCUMENTS, which is hereby incorporated by reference into thisapplication.

Alternatively, the topic generation program 18 uses a clusteringalgorithm, such as the k-means algorithm, to identify topics orcategories for the documents 13 and compute relatedness or closenessvalues such as centroid vectors which indicate how relevant a givendocument is to the topic. Each document may be related in differentdegrees or strengths to different topics, and each topic may contain anumber of documents. Such a program is described for a chat document inco-pending commonly owned U.S. patent application Ser. No. 09/143,075titled METHOD AND SYSTEM FOR INFORMING USERS OF SUBJECTS OF DISCUSSIONIN ON-LINE CHATS filed Aug. 28, 1998, and more generally in U.S. Pat.No. 5,924,105, issued Jul. 13, 1999, titled METHOD AND PRODUCT FORDETERMINING SALIENT FEATURES FOR USE IN INFORMATION SEARCHING, both ofwhich are hereby incorporated by reference into this application.

The user profile repository 16 is a directory containing data aboutusers that is used as an authoritative source of organizational or groupmembership of an such as a company or otherwise as a repository of userprofiles. As is known, a profile is a database record containing dataabout a user such as the user's identity, location, phone numbers, emailaddresses, security credentials, etc. The repository 16 may be a specialprofile database, such as a Lotus DOMINO database, or it may be anextension of an organization's existing directory, such as an LDAPdirectory or Microsoft's Exchange messaging directory. The systemfurther contains an address directory 20 which receives information fromusers 11 and which is synchronized with the profile repository 16.

In accordance with the invention, the system 10 contains additionalcomponents to support the dynamic assessments of and publication aboutuser affinities to topics. As shown in FIG. 1, additional profileextensions 22 are attached to the user profiles in the profilerepository 16 to store information about each user's affinity tocontent. In one embodiment, the system 10 programmatically extends thedesign schema of the repository 16 to include affinity results, privateand published as described below, and reads the directory to establish alist of target users. External users such as contract workers can beadded to the directory for expertise tracking only, if desired. In someembodiments, the extended profile is based on the Lotus DOMINO directoryand extensions to the directory's person record. In Microsoftenvironments, the DOMINO directory is synchronized with the MS Exchangedirectory and/or the Win2000 Active Directory, or both.

The additional information in the profile extensions include, in oneembodiment, a ranked list of the top ten affinities for the user. Asdescribed further below, an affinity is a variable such as a numberwhich represents the strength of a user's connection to a topic asrepresented by the user's activities on various of the documents 13, andmay include additional information as described below. Also as explainedfurther below, the user is provided control over maintenance, approvaland publication of affinities.

The affinities are generated by usage metric software routines 24 whichgather document metadata from the document management system 12 andcontent catalog 14, stores it in compact form in a relational usagedatabase 26, and analyzes the stored data in accordance with a desiredalgorithm. As shown in FIG. 1, the document metadata stored in the usagedatabase 26 includes users who have performed activities over the system10, documents created by, attributed to, or otherwise used by the users,as determined from the document management system 12, and topicsassigned to those documents as determined from the content catalog 14 asdescribed above. The usage metrics 24 use the stored data to generateaffinities between topics and users and under certain conditions storethose affinities in the profile extensions 22.

The system further includes an approval agent 28, which is a softwareroutine that monitors profiles for affinities and requests approval fromusers to publish their affinities so other users may become aware ofthem. A publication agent 30 is a software routine which publishesapproved affinities to the content catalog 14 by either inserting theuser profiles 32 for the approved affinities into the catalog 14 orcreating links to the user profiles 32 for the approved affinities tothe topics associated with the affinities in the catalog 14.

An exemplary process performed by the system of FIG. 1 is describedgenerally with reference to FIG. 2 and then more particularly withreference to FIGS. 3A-3D. If a user creates a new document, step 40, oneor more topics are generated for the document, step 42. If a usermanipulates an existing document, the one or more previously assignedtopics contained in the content catalog are retrieved, step 46. In someembodiments, certain users, such as system administrators who accessmany documents, may be identified as nonaffinity generating and thustheir activities would be ignored. The affinity strength representingthe relationship between each of the topics assigned to the document isupdated to reflect the user's increased affinity to the topics, step 46.In a simple embodiment, the affinity strength is represented an integerwhich is incremented for each document created or used by the user. Morecomplex embodiments, such as the one described below, consider a varietyof additional factors including the document's closeness to each topic,the frequency with which the user accesses documents in this topic, andthe level of affinity by other users to the same topic. That is, thecloser the document is to the topic; the more frequently the useraccesses documents in the topic; and the lower the general level ofaffinity by others—the greater the user's increase in affinity strengthwill be.

If the affinity strength reaches or exceeds a threshold, step 50, whichthreshold may be predefined or set dynamically depending upon thecircumstances, the affinity is added to the user's extended profile,step 52. If the user consents to publication of the affinity, step 54,the affinity is published to the content catalog, step 56. Other userswho perform searches for the topic through the content catalog are theninformed of this user's affinity to and potential status as an expert inthe topic. If the user does not approve publication of the affinity, theaffinity is stored in the user's extended profile, step 58, for use inidentifying the affinity as nonapproved to thereby prevent continuousrequests for approval or to serve as a basis for comparison as theaffinity strength increases to support an additional request forapproval.

Referring now to FIG. 3A, a more detailed description of the processstarts with users of the system registering their profile information inthe address directory, step 70. The profile repository is synchronizedwith the address directory, step 72, to establish a reliable,authoritative source of user profile information. The profile repositoryreflects the community of expertise that the system 10 will createaffinities for, and may include people outside of an organization whoare not in the directory.

If a user creates a new document, step 74, the topic generator generatesone or more topics and closeness values, such as centroid vectors,between each topic and the document, step 76. It further updates thecontent catalog with the new topic/document relationships, step 78.

In addition to authorship, the system 10 can provide a deeper, moreexpansive and more accurate set of affinities by profiling the user'suse of other data sources such as email, discussion databases, and othercollaborative tools by which content may be publicly accessed.Typically, this requires the user's permission and privacy controlmechanisms. Once permitted, the system examines authorship, documentactions such as filing, forwarding, deletion, etc., document reaction,e.g., responses/replies, content reuse, e.g., incorporation into newdocuments, and citations, e.g., ‘bookmarking’, created links to thesource, etc., and builds a refined set of document valuations. Whenanalyzed against the catalog topics, this additional evidence providesthe user and the system with a detailed affinity set.

Thus, if a user accesses or manipulates an existing document, step 80,the system determines whether the topic(s) associated with the documentsare to be updated as a result, e.g., the document is edited, step 82. Ifso, the topic generation process is initiated, step 76 and contentcatalog updated accordingly, step 78. As a result, the content catalogcontains the most up-to-date representations of the topics associatedwith the affected document.

The usage metrics routines query the catalog for the topical categoriesthat the document has been classified under, step 84, and uses theresult to build or modify the association table or usage database ofprofiled authors and the documents that they have created or accessed,step 86. As explained above, a document may be ‘soft classified’ undermultiple categories or topics depending on the range of content in thedocument. As documents are processed by the usage metrics component,typically after indexing and classification in the content catalog, theassociation table gets populated.

At a scheduled interval, step 88, the usage metrics component analyzesthe associations for each profiled user and computes the strength of theassociation. Thus, the usage metrics routines open the usage database,step 90 (FIG. 3B), and, for each user in the usage table and for eachtopic associated with the user, finds the number of documents associatedwith the topic, step 92. A topic affinity count is incremented, step 94,which represents the number of affinities associated with the topicacross all users, for use as explained below. For each document listedas associated with the topic, the closeness value between the documentand topic is retrieved from the content catalog, step 96, and metadataabout the document, including dates and times of creation and otheraccess by the user is retrieved, step 98, from the document managementsystem. This information is retrieved for each document until nodocuments remain for the topic, step 100. The usage metric routine thencomputes several numbers for the set of documents, including an averagecloseness value among documents in the topic, a decay time derived fromthe average amount of time that has passed since the documents werecreated/accessed, and a frequency by which the documents in the topicwere created/accessed, step 102.

This process is repeated for each topic associated with the user untilnone remain, step 104, and for each user in the usage table until allusers have been processed, step 106. An affinity density is thencomputed for each topic, step 108 (FIG. 3C), which represents the totalinstances of affinity across all users for the topic as a ratio of alltopical affinities. This number helps indicate whether the topic willgenerate too many affinities and is thus too general to be of practicaluse to other users.

For each user and topic, the usage metrics routine computes an affinitystrength, step 110. In one exemplary embodiment, this computationinvolves the variable retrieved and calculated above and is performedaccording to the following equation:Affinity strength=(Doc.#*Freq.*Decay*CV)/TADwhere:

-   -   Doc. # is a value representing the number of authored documents        that are classified in the topic category (the more documents,        the greater the affinity should be);    -   Freq. or Frequency is a value representing how often documents        are authored by the user in this topic (greater frequency        implies greater affinity);    -   Decay is a value derived inversely from the average age of the        authorship of the documents (older documents having less value        in the support of affinities);    -   CV or Centroid Vector is a value representing the closeness of        the document content to the topical catalog category, as        generated by the topic generation program (greater closeness        values imply greater affinity); and    -   TAD or Topic Affinity Density is a value representing the number        of affinities published for each category across all users over        the total number of affinities.

As one skilled in the art will recognize, a given affinity generationsystem may consider more or less factors and may weight them differentlyto reflect a desired goal within the set of users. For example, asdescribed herein, the system preferably considers creation of andchanges made to documents as affinity generating events. However,certain systems such as library systems or the world wide web may placegreater emphasis on accessing or downloading documents and the timespent doing so rather than attempting to change documents. Such accessmay be the basis for computing affinity values. Similarly, in anelectronic commerce system, events such as purchases, co-purchases,viewing or interacting with ads, or product inquiries may be used tocompute affinity values.

If the affinity strength so computed is greater than a threshold, whichmay be dynamically determined by the system or set via a policydocument, step 1112, an affinity is written into a private section ofthe user's profile, step 114, so as to be accessible only by the userhimself and not other users. The process of computing affinity strengthsand determining their status is repeated for each topic, step 116, andeach user, step 118.

At periodic intervals, the approval agent runs to identify and processnew ‘proposed’ affinities in user profiles extensions, step 120. Anaffinity is determined to be new by the usage metrics routine bycomparison with existing affinities stored in the user's profile, and aflag may be set to indicate its status as new. The agent sends theprofiled user a request for approval of the affinity such as by emailnotification, step 122. The user may open his profile and decide toeither publish this affinity or to suppress it, step 124. If approvedfor publication, the approval agent moves the affinity into a publicsection of the user's profile, step 126, so the affinity will beviewable and searchable in the user's profile. This process is repeatedby the approval agent for all profiles having new affinities, step 128.

Periodically the catalog publication agent identifies and collects new‘published’ affinities, step 130 (FIG. 3D) and creates link documents inthe content catalog for the person which will provide a link to theperson's profile, step 132. This is repeated for all profiles with newpublished affinities, step 134.

If the user chooses to suppress the affinity, it is kept in the profileand used as a filter to avoid repeated affinity proposals. In oneimplementation of the system, users are allowed to declare specificaffinities. This is done through the content catalog interface, whichdirectly writes the affinity in the ‘published’ state to the user'sprofile. System administrators can also designate affinities through thecontent catalog's taxonomy editor interface, which also writes theaffinity to the user's profile. The process of approving and publishingaffinities can be controlled from a policy document, where timeouts canbe set to override user's who do not respond to the affinitynotification. Until the affinities are approved and published by theuser or via a policy proxy, they are kept in a coded numerical form forprivacy within a restricted section of the profile document. The sametreatment is applied to the affinity suppression list.

Until the affinity is published by the user, the affinity is stored inthe user's profile in a numerical, tuple form to avoid detection by fulltext searches. The tuple contains a topic ID, a unique catalog ID forthe topic (e.g., from DB/2 catalog); a source code; the affinitystrength (e.g., a number from 0 to 1); a heuristic mask (a set of flagsfor privacy, publishing, etc.). A sample affinity tuple format is shownbelow is Table I:

TABLE I AFFINITY TUPLES Component Description Topic ID Unique topic IDSource Code Integer:  0 = Computed by usage metrics  1 = User declared 2 = Management designated  3-6 = reserved  7-9 = for third party useAffinity strength Float from 0 to 1, where:  0 = no affinity  1 =highest affinity (universal expert) Heuristic mask An extensible integermask, where:  First digit = Suppress state (1 = Keep private)  Seconddigit = Review state (1 = reviewed or  overwritten by policy)  Thirddigit = Publish state (1 = Publish to catalog) For example:  000 = new,not reviewed or publishable  010 = reviewed, but not publishable  001 =published (used for declared affinity)  1XX = suppressed, but stored.

This is the basic affinity of one embodiment. It is written into the‘Proposed Affinities’ field of an extended user profile, one affinityper line, comma delimited, after the module checks to see that the topicID isn't already present in the published or suppressed fields. Theproposed field is hidden from public view where affinities are heldpending user review. The usage metrics module does all the work anderror checking.

From the content catalog a user can find people and documents by eitherbrowsing or searching. In either case, people will be represented in amanner similar to documents, either tersely (e.g., name, title, email,etc.) or verbosely (name, title, phone, email, location, Lotus SAMETIMEstatus, etc.) An exemplary screen display showing documents and usersassociated in the content catalog with the topic “JavaScript” andlocated as a result of search through the catalog is shown in FIG. 4. Asshown in FIG. 4, a document listing 150 is generated and displayedincluding closeness values expressed as percentages, and a user affinityor expert list 160 is generated and displayed with users ranked byaffinity strength and identified in this embodiment only by name.

The names in the user expert list 160 are hyperlinked to user profiles,so that clicking on a selected user name would bring up the profile in aseparate window, either a business card or full profile depending oncontext, with full profiles being brought up in embodiments with a moreverbose listing of experts. An exemplary user profile screen display isshown in FIG. 5. Additionally, graphical hooks 180 for chat and emailare integrated as shown in FIG. 5 by implementing links or iconswherever a person is represented in the content catalog, and anavailability icon 190 is displayed indicating the person's availability.For example, the email addresses will be computed into a mailto: URL.The chat, email and availability tools may be supported by variousexisting software collaboration and messaging products such as LotusSAMETIME or the like.

While the invention has been described and illustrated in connectionwith preferred embodiments, many variations and modifications as will beevident to those skilled in this art may be made without departing fromthe spirit and scope of the invention, and the invention is thus not tobe limited to the precise details of methodology or construction setforth above as such variations and modification are intended to beincluded within the scope of the invention.

1. A computer implemented method for profiling a user based on theuser's activity, the method comprising: assigning one or more topics toeach of a plurality of documents based at least in part upon contentcontained in the documents; maintaining an affinity variable associatedwith the user for each of one or more of the topics assigned to adocument attributed to the user, wherein the affinity variable is acalculated value linking the user to each of the one or more topicsassigned to the documents, the affinity variable being calculated usinga mathematical function; determining whether a first affinity variablefor the user for a given topic has reached a threshold; associating theuser with the given topic for the first affinity variable which reachesthe threshold; and updating the affinity variable for a first topic foreach document created by the user to which the first topic is assignedto maintain the affinity variable, the maintaining including weightingeach document created by the user based upon one or more factorsincluding a number of documents to which the first topic is assigned, aperiod of time over which the documents were created by the user, and acloseness of each document to the first topic.
 2. The method of claim 1,wherein the step of maintaining the affinity variable for the usercomprises adjusting the affinity variable based upon affinity variablesassociated with a plurality of second users for the first topic.
 3. Themethod of claim 1, comprising updating the affinity variable for a topicbased upon the user's manipulation of a document to which the topic isassigned.
 4. The method of claim 3, wherein the user's manipulations areselected from the group consisting of adding content to the document,deleting content from the document, sending the document to anotheruser, bookmarking the document, and modifying document metadata.
 5. Themethod of claim 3, wherein the user's manipulations comprise addingcontent to the document and deleting content from the document,comprising assigning a topic to the document based upon content added toor deleted from the document, and wherein the step of maintaining theaffinity variable comprises updating the affinity variable for the topicassigned to the document based upon the added or deleted content.
 6. Themethod of claim 3, comprising assigning one or more second topics to adocument based upon content in the document following the user'smanipulation thereof, and wherein the step of updating the affinityvariable comprises updating the affinity variable for the one or moresecond topics.
 7. The method of claim 6, comprising allowing theplurality of users to access the content catalog to identify the user'sassociation with the given topic.
 8. The method of claim 7, comprisingestablishing communication between the user and one or more of theplurality of user who have identified the user's association with thegiven topic.
 9. The method of claim 1, comprising storing a contentcatalog accessible by a plurality of users, which content catalogcontains topics associated with documents to which the topics areassigned, and wherein the step of associating the user with the giventopic comprises associating the user with the given topic contained inthe content catalog.
 10. The method of claim 9, wherein the step ofmaintaining the affinity variable comprises storing the affinityvariable in a profile associated with the user.
 11. The method of claim10, comprising requesting the user's approval as a condition toassociating the user with the given topic contained in the contentcatalog.
 12. The method of claim 11, comprising storing the firstaffinity variable in the user's profile if the user declines to approveassociation of the user with the given topic in the content catalog. 13.The method of claim 1, wherein the step of maintaining the affinityvariable comprises updating the affinity variable to reflect a passageof time.
 14. The method of claim 13, wherein the affinity variable isnumerical and wherein the step of maintaining the affinity variablecomprises increasing the affinity variable for each topic assigned to adocument attributed to the user and decreasing the affinity variable toreflect the passage of time.
 15. A computerized system for profilingusers based on their affinity to content, the system comprising: acontent catalog stored on a memory device which associates documentswith topics; one or more usage metric routines executable by thecomputerized system for maintaining an affinity value for each user foreach of one or more topics assigned to documents attributed to the user,wherein the affinity variable is a calculated value linking the user toeach of the one or more topics assigned to the documents, the affinityvariable being calculated using a mathematical function; a plurality ofuser profiles stored on a memory device containing affinity valuesmaintained for the users; and a publication agent executable by thecomputerized system for associating certain topics in the contentcatalog with certain users based at least in part upon the affinityvalues contained in the user profiles; wherein the computerized systemmaintaining the affinity variable includes updating the affinity for afirst topic for each document created by the user to which the firsttopic is assigned, including weighting each document created by the userbased upon one or more factors including a number of documents to whichthe first topic is assigned, a period of time over which the documentswere created by the user, and a closeness of each document to the firsttopic.
 16. The system of claim 15, comprising an association tablestored in a memory device containing sets of data relating each user totopics and the documents associated therewith, the association tablebeing accessed by the one or more usage metric routines in maintainingthe affinity values.
 17. The system of claim 15, wherein the userprofiles contain only affinity values which have reached a threshold.18. A computer readable medium containing program code for, whenexecuted by a computer, causing the computer to perform a method forprofiling a user based on the user's activity, the method comprising:assigning one or more topics to each of a plurality of documents basedat least in part upon content contained in the documents; maintaining anaffinity variable associated with the user for each of one or more ofthe topics assigned to a document attributed to the use, wherein theaffinity variable is a calculated value linking the user to each of theone or more topics assigned to the documents, the affinity variablebeing calculated using a mathematical function; determining whether afirst affinity variable for the user for a given topic has reached athreshold; associating the user with the given topic for the firstaffinity variable which reaches the threshold; and updating the affinityvariable for a first topic for each document created by the user towhich the first topic is assigned to maintain the affinity variable, themaintaining including weighting each document created by the user basedupon one or more factors including a number of documents to which thefirst topic is assigned, a period of time over which the documents werecreated by the user, and a closeness of each document to the firsttopic.